Vehicles having four-wheel drive capabilities that are designed for on-road and off-road use typically provide optional engagement/disengagement of two of the four wheels. The wheels to be disengaged are necessarily provided with a driveline from the vehicle powertrain wherein for on-road use and to avoid unnecessary energy consumption and wearing of the out-of-service driveline components, hub locks are provided for disconnecting the axles from the wheels of the vehicle. The original hub lock devices were manually actuated. A driver/operator would stop the vehicle, engage the transfer case disconnect system and then manually turn a dial located in each wheel hub to activate the hub lock to disconnect the wheels from the axles.
Subsequently, mechanisms have been developed to automatically activate the hub locks. Automatic locking hubs for four-wheel drive vehicles are now available in many different design configurations. Such configurations include direct manual clutch engagement, remote vacuum clutch engagement, and remote pressure clutch engagement. The systems of the previous designs include complex designs requiring numerous parts involved that render the device expensive to produce and/or are complex to assemble. The present invention requires fewer parts for more efficient production, a more compact package of components for easier assembly to the vehicle, and reduced unsprung mass.
The vacuum locking hub assembly of the present invention includes a body member having an annular base portion secured to an inner drive gear. The inner drive gear includes internal splines in engagement with the external splines of the axle shaft and a plurality of exterior clutch teeth. A clutch ring surrounds the inner drive gear and includes internal clutch teeth with the clutch ring being slidable relative to the inner drive gear for moving the internal clutch teeth into and out of engagement with the exterior clutch teeth of the inner drive gear. A piston is received in the body member and is disposed against the clutch ring for causing driving movement of the clutch ring. A diaphragm is attached to the body member by a retainer and acts against the piston for driving the piston. The inner drive gear, clutch ring, piston, and diaphragm are all held together by the body member as a cartridge unit.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes, of illustration only and are not intended to limit the scope of the invention.